The present invention relates to an expanded tube processing method and an expanded tube processing apparatus of a cylindrical tube.
There has been heretofore a case in which an expanded tube portion having an axis inclined with respect to a tube axis of a cylindrical tube (tube) is formed on an end of the cylindrical tube (tube) of a metal.
For example, in an exhaust tube in automotive parts and the like, in order to secure a path in a limited space under a vehicle floor, as shown in FIG. 18, one tube 101 is connected to another tube 102 at a reduced diameter portion 103 in such a manner that a tube axis B of another tube 102 is inclined with respect to a tube axis A of the one tube 101. When such a connection is performed, for example, as shown in FIG. 19, there may be used such a connection tube that a gradually changing portion 105 is formed at a tip end of a rare tube 104 of a cylindrical tube consisted of a metal tube by expanding the tube, and an expanded tube portion 106 for connection is continuously formed at the tip end of the gradually changing portion 105, tube axes C, B of the gradually changing portion 105 and the expanded tube portion 106 are inclined with respect to the tube axis A of the rare tube 104.
Additionally, a gradually changing portion 107 may be integrally formed beforehand on a side opposite to the expanded tube portion 106 in the rare tube 104 as shown in FIG. 18.
FIGS. 20 and 21 discussed below were developed by the present inventors in the process of inventing the method and apparatus of the present invention.
Moreover, a process is considered in which a usual punch is utilized in a method of molding the gradually changing portion 105 and expanded tube portion 106 with the inclined tube axes on the tip end of the rare tube 104. Specifically, as shown in FIG. 20, considered is the process comprising: molding an enlarged diameter portion 105a concentric with the tube axis A of the rare tube 104 beforehand on the end of the rare tube 104; holding and fixing a work W formed of the rare tube 104 and enlarged diameter portion 105a with a forming die 108 in such a manner that the tube axis A slopes with respect to a vertical line B as shown in FIG. 20; simply lowering a punch 110 with an inner die surface 109 formed on a lower surface thereof only in a vertical direction to insert the punch into the enlarged diameter portion 105a; and using the inner die surface 109 and an outer die surface 111 of the forming die 108 to press-mold the enlarged diameter portion 105a on the gradually changing portion 105 and expanded tube portion 106 inclined with respect to the tube axis A.
However, according to this process, as shown in FIG. 21, the inner die surface 109 of the punch 110 is provided with a portion 109a which interferes with an opening end surface 105b of the enlarged diameter portion 105a, and the enlarged diameter portion 105a collapses and causes a problem that an expanded tube processing is not established.
In order to prevent the aforementioned interference, it is also proposed to utilize a known slant cutting die as shown in FIG. 22. This process comprises the steps of: forming a slant hole 202 in a punch guide 201; disposing a punch 203 in the slant hole 202 in a slidable manner and also disposing a return spring 204; striking a head of the punch 203 with a cam block 205 to move the punch 203 in a slant downward direction; and piercing an inclinedly disposed work 206.
When this process is applied to an enlarged diameter processing of the gradually changing portion 105 and expanded tube portion 106, no interference problem described with reference to FIG. 21 occurs. However, the large punch guide 201 is necessary and this is uneconomical. Furthermore, every time differences in a tube axis angle and an expanded tube shape between the gradually changing portion 105 and the expanded tube portion 106 are handled, a new punch guide 201 needs to be provided, which causes a problem that installation expenses also increase.
If the aforementioned conventional apparatus is utilized to form the gradually changing portion and expanded tube portion inclined with respect to the tube axis of the rare tube, the aforementioned respective problems occur. There have been demanded an expanded tube processing method and apparatus which can subject the inclined gradually changing portion and expanded tube portion to the expanded tube processing with a simple constitution.
Wherefore, an object of the present invention is to provide an expanded tube processing method and an expanded tube processing apparatus in which an expanded tube portion provided with a tube axis having an angle with respect to a tube axis of a rare tube can be processed with good precision.
In order to solve the aforementioned problems, according to a first aspect of the present invention, there is provided an expanded tube processing method of a cylindrical tube in which a punch is disposed on the side of an opening end of a work formed of a metal cylindrical tube and the punch is inserted from the opening end of the work to enlarge the diameter of an end of the work, the method comprising steps of: inserting the punch from the opening end of the work at a predetermined angle with respect to a tube axis of the work; and moving the punch and/or the work during insertion of the punch in a direction substantially crossing at right angles to a punch insertion path to perform an expanded tube processing.
In the expanded tube processing method according to the present invention, a work opening end surface on the side of insertion of the punch may also be formed to be substantially at right angles to the insertion path of the punch.
Moreover, in the expanded tube processing method according to the present invention, the work may be inclined and held with respect to the vertical direction, the insertion path of the punch is vertical, and movement of the punch and/or the work in the direction substantially crossing at right angles to the work insertion path can be a movement of a horizontal direction.
Furthermore, in the expanded tube processing method according to the present invention, the movement of the direction substantially crossing at right angles to the punch insertion path in the punch and/or the work may also be performed in at least two directions.
Moreover, in order to solve the aforementioned problems, according to a second aspect of the present invention, there is provided an expanded tube processing apparatus of a cylindrical tube, in which a punch is disposed on the side of an opening end of a work formed of the cylindrical tube of a metal and the punch is inserted from the opening end of the work to enlarge the diameter of an end of the work, the apparatus comprising: a forming die for holding the work in an inclined state with respect to a punch insertion path; driving means for moving the punch in a direction of the insertion path; and a support mechanism for supporting the punch and/or the work in a direction substantially crossing at right angles to the insertion path of the work in such a manner that floating is possible.
Furthermore, in the expanded tube processing apparatus according to the present invention, a work opening end surface on the side of insertion of the punch may also be formed to be substantially at right angles to the insertion path of the punch.
Additionally, in the expanded tube processing apparatus according to the present invention, the forming die for the work is formed to incline and hold the work with respect to a vertical direction, the insertion path of the punch is set in a vertical direction, and a floating direction of the punch and/or the work can also be set to a horizontal direction.
Moreover, in the expanded tube processing apparatus according to the present invention, the floating direction of the punch and/or the work may also be set to at least two directions.
Additionally, the expanded tube processing apparatus according to the present invention may also be provided with return means for returning the punch and/or the work to an original position side on which the tube expansion starts in the floating direction.
Moreover, in the expanded tube processing apparatus according to the present invention, the return means mentioned above may be urging means for constantly urging the punch and/or the work to the original position side.
Furthermore, in order to solve the aforementioned problems, according to a third aspect of the present invention, there is provided an expanded tube processing apparatus of a cylindrical tube, in which a punch is disposed on the side of an opening end of a work formed of the cylindrical tube of a metal and the punch is inserted from the opening end of the work to enlarge the diameter of an end of the work, the apparatus comprising: a forming die for fixing/holding the work in such a manner that an end of the work is inclined with respect to a punch insertion path; driving means for moving the work in a direction of the insertion path; and a support mechanism for supporting the punch in a direction substantially crossing at right angles to the insertion path of the work in such a manner that floating is possible.